In the disclosure of the present invention reference is mostly made to liquids in the form of medical liquids as outlined above, however, this is only an exemplary use of the present invention.
A medical liquid is often supplied in a reservoir (e.g. a container, bag or bottle) which can be accessed by means of a hollow needle, the needle typically penetrating a dedicated connection element (or access means) of the reservoir to provide a fluid communication with the interior of the reservoir. The needle access may be used either for withdrawing liquids from the reservoir or for supplying a liquid to the reservoir. For example, when preparing the fluids which are to be administrated to the body of a patient from a given reservoir, it is common that medically effective substances are supplied to a pre-sealed reservoir which is filled with a transport fluid, usually in the form of sodium chloride solution or a glucose solution, the diluted drug then being given to a patient intravenously via an intravenous (IV) infusion set. For this type of use, the reservoir may be provided with a single connection means adapted to be used for both purposes, or the reservoir may comprise two connection means adapted for their respective purposes, e.g. for a larger infusion set outlet needle and a smaller drug injecting needle. The connection element may be adapted to be opened manually to provide an opening, through which a needle subsequently can be inserted, or the pointed needle can be used for penetrating the connection element, which may be of the self-sealing type, e.g. the connection element will seal the reservoir after the needle has been withdrawn.
In case the reservoir is of glass, the connection element will be a separate element which is mounted to the glass reservoir by special means, however, for plastic reservoirs the connection element will typically be formed integrally with the reservoir. One of the most widely used type of plastic reservoirs for medical use is in the form of a flexible infusion bag comprising at a lower portion thereof one or more needle-penetratable connection elements. Such bags are typically formed from flexible foil sheets which are joined to form an internal space. Depending on the actual construction of the bag, the connection element(s) may be arranged either on a surface portion of a foil sheet or may be arranged corresponding to an edge portion of the reservoir. For the latter type, the connection element is typically positioned and held in place between two foil sheets connected to each other by welding.
For both of the above two arrangements, the self-sealing element is normally carried by a tubular member connected to the bag in either of the above two ways. For example, U.S. Pat. No. 4,362,158 shows an infusion bag in which a tubular nozzle member is connected to an infusion bag corresponding to a free surface thereof, a self-sealing rubber seal member being mounted on the nozzle.
For some liquids, e.g. certain types of drugs, it is desirable if the elastomeric material from which the seal member normally is manufactured, does not come in contact with drug. To solve this problem, European patent application EP 0 364 783 describes a medicament bottle having an external sealing element held in place by a separate cap member attached to the outer surface of the bottle, and FR 2 752 410 discloses a medicament bag in which a needle-penetratable member is attached to an outer surface of the bag.
U.S. Pat. No. 6,074,369 discloses an injection device comprising a flexible reservoir formed from two Belleville spring diaphragms and with a needle-penetratable member arranged between the two diaphragms. The reservoir is mounted in a housing by mounting means engaging the diaphragms.
The above reservoirs are relatively large typically comprising 100-1000 ml of liquid, however, reservoirs which can be accessed by a penetrating needle member is also used for much smaller volumes. For example, certain calibration solutions for calibrating analytical equipment are supplied in small bag-like reservoirs containing a few ml. When properly designed, such small reservoirs may also be used for drug purposes.